RO/DI filters

[Fireworm]

I have an older RO unit that was given to me. I have no idea how old the membrane is or even what it is rated for. I changed the carbon and put in new DI last year at one point, and used it with great success for a while. I then tore down my 90 and went without a tank for several months. I have since then set up my newer smaller tank, and test my TDS for the first time. I was at around 35 for RO and down to 24 with the DI. My question is can I get by with just changing out the carbon and DI again, or do I need a new membrane. My water runs through my whole house filter before the RO unit, and that has a carbon filter in it that gets changed once a month if that makes any difference.

[tkeracer619]

IME get all new filters and a membrane.

35 for a RO membrane that has been sitting for a while is not too bad. I would take out the restrictor in the drain line and run it for 10 minutes like that, it will fast flush your membrane and maybe add some life into it.

If you have a water softener a properly cared for membrane could last 5+ years. It will be worth it to swap IMO.

[Fireworm]

I don't have a softener, just a whole house filter. Looks like the filter housing for the RO filters, just has a carbon/sediment filter in it from Lowes. My water is horrible with out it. You can see things float in your tap water without it. I am the only gut on the block that put one in when we first built the house, and I am the only guy who has not replaced my hot water heater or other appliances. Knock on wood.

The restrictor in the drain line, I looked and I don't think there is one there. I had to replace all the lines and a couple of the fittings when I got it, and I wonder if it got pitched some how doing that.

Am I better off to buy new filters and membrane, or just get a new system all together? And to replace them, I have looked at bulk reef supply, is there someone else I should be looking at for this stuff.

[tkeracer619]

Bulk reef supply is a good source for filters. Filter guys, Air water ice, spectrapure... they all sell good stuff. No need to get a new system all together, the one you have is fine.

A restrictor will either be a push in fitting on the waste line or a tiny tube inside the tubing at the waste water fitting. Without it you will hardly make any water.

Ordering something like this will give you a new restrictor and a fast flush valve in one.
http://www.airwaterice.com/product/F...estrictor.html

[Fireworm]

Thanks. I will try that. How about the flush kits... I have heard yes that you need them and should flush everyother week or so, or no its a waste of time and money

[tkeracer619]

It might or might not be a waste of money depending on what its worth to you. Do you want to disconnect the waste water line and remove the restrictor every time you want to flush it? If you don't mind then they are a waste. Otherwise i like being able to turn a lever once a month and flush it without doing anything else.

I don't actually know how often you are supposed to do it. I do it about once a month or whenever tds starts to creep up on me.

[Fireworm]

and the flushing seems to help with that?

Also, do you check your TDS after the ro and the di or do you just check after the DI

[tkeracer619]

Flushing helps the membrane last longer afaik. Seems to drop the tds a few points as well if the membrane has tds creep. Though that might just go away on its own if it were to run for a while, not 100% sure.

I check TDS in 3 spots.

Faucet with a handheld.
Between RO and DI
After DI

The ratio between faucet and ro tds will tell you if your membrane is up to par. Pull the membrane out and take a look to see what it is. Check online for rejection rates and compare.

I run a dual DI setup. Both are mixed bed medias. When the first one starts to creep up (I put my tds meter between the two) I put the second cartridge in its place and refill the 1st cartridge. I then put the refilled cartridge in the 2nd slot.

[Fireworm]

I checked my TDS at one time at the tap and it was around 420... just about to the legal limit

[tkeracer619]

Holy cow. I think I would have a RO pressure tank and a faucet on the sink with tds like that for drinking water.

Do you have good pressure? You should be closer to 8TDS out of your ro if it is a filmtec. A dual DI would probably be a good idea as well if you always want 0tds.

[Fireworm]

I had 0 TDS when I first changed all my filters, so I can do it with the setup, but I am sure my DI gets eaten up rather quick. And no, my pressure sucks for the most part. can not say 100% for sure what it is, but I am the last house on my water line, and you can tell.

[tkeracer619]

You can re-activate DI resins pretty easy. Might look into it.

[SpectraPure]

Fwiw- another consideration, you can save considerable money on your DI stages by refilling your own DI cartridges.
http://www.spectrapure.com/email/cus...ciation.html#1
There has been some pretty good advice already on this thread. I would add that in our experience almost every persons usage, operation conditions, and source water is different that we always encourage you to measure and test your way thru filter changes, membrane checks, and DI replacements (ala theracer619). This way you can establish for yourself optimal operation points to maximize your water production and quality while maintaining an appropriate maintenance cost for your consumable. This is the classic trade off. For example, regarding membrane rejection http://www.reefcentral.com/forums/sh....php?t=1336345

or in the case of TDS creep:
http://www.reefcentral.com/forums/sh...d.php?t=260522

Both of these threads offer at least several of the many considerations that directly relate to your cost to maintain your system.
Hope this helps.
bruce
bruce